Selenide nanocrystals are important materials with applications throughout electronics, solar cells, light emitting diodes (LED), and biology. These materials range from elemental to binary, tertiary, and quaternary compounds and involve elements throughout the periodic table. Despite the variety of metal precursors, reaction solvents, and temperatures there is a general singularity of the selenium source coming from dissolved/reacted selenium in tri-octyl phosphine (TOP). TOP has limitations to use due to the cost, stability, and toxicity, but importantly also due to the possibility of phosphorous incorporation and contamination of the final material under reaction conditions.
Many attempts have been made to replace TOP, but each faces significant limitations. Organoselenide chemicals are generally toxic and unstable. Soluble selenium in ethylenediamine is limited by the low boiling point temperature of the solvent and general poor solubility. Oleylamine (OLA) used alone can only dissolve small quantities of selenium and only at higher temperatures due to the relatively weak reducing ability of amines unless coupled with a reducing agent such as the alkali borohydrides which then introduces boron and alkali ion contaminants to the system, altering growth mechanisms as well as electronic properties.
Therefore, there is an unmet need for need for a homogeneous solution to reproducibly generate controlled size nanoparticles.